Battery power management systems and methods for engine off

Abstract

An air conditioning system of a vehicle having an internal combustion engine includes a condenser configured to receive refrigerant output by an electric compressor and transfer heat from the refrigerant within the condenser to air passing the condenser. A first evaporator is configured to receive refrigerant from the condenser when a first control valve is open and transfer heat from air passing the first evaporator to the refrigerant within the first evaporator. A first blower is configured to blow air across the first evaporator to a first section of a cabin of the vehicle. A second evaporator is configured to receive refrigerant from the condenser when a second control valve is open and transfer heat from air passing the second evaporator to the refrigerant within the second evaporator. A second blower is configured to blow air across the second evaporator to a second section of the cabin of the vehicle.

What is claimed is: 
     
       1. An air conditioning system of a vehicle having an internal combustion engine, comprising:
 an electric compressor that draws power from a battery pack; 
 a condenser that is configured to receive refrigerant output by the electric compressor and that transfers heat from the refrigerant within the condenser to air passing the condenser; 
 a first control valve; 
 a first evaporator that is configured to receive refrigerant from the condenser when the first control valve is open and that transfers heat from air passing the first evaporator to the refrigerant within the first evaporator; 
 a first blower that is configured to blow air across the first evaporator to a first section of a cabin of the vehicle; 
 a second control valve; 
 a second evaporator that is configured to receive refrigerant from the condenser when the second control valve is open and that transfers heat from air passing the second evaporator to the refrigerant within the second evaporator; 
 a second blower that is configured to blow air across the second evaporator to a second section of the cabin of the vehicle; and 
 a control module that is configured to, when the internal combustion engine of the vehicle is off, the electric compressor is on, and the second blower is on and blowing air across the second evaporator, control a speed of the electric compressor based on at least one of: 
 a temperature of the second section of the cabin of the vehicle; and 
 a speed of the second blower, 
 wherein the control module is configured to, based on a current of the electric compressor, determine whether to control the speed of the electric compressor based on the temperature of the second section of the cabin of the vehicle or based on the speed of the second blower. 
 
     
     
       2. The air conditioning system of  claim 1  wherein the control module is configured to:
 when the current of the electric compressor is greater than a predetermined value, control the speed of the electric compressor based on the temperature of the second section of the cabin of the vehicle; and 
 when the current of the electric compressor is not greater than the predetermined value, control the speed of the electric compressor based on the speed of the second blower. 
 
     
     
       3. The air conditioning system of  claim 2  wherein the control module is configured to, when the current of the electric compressor is greater than the predetermined value:
 (i) operate the electric compressor at a predetermined speed until the temperature of the second section of the cabin is less than a minimum temperature defining a lower limit of a predetermined temperature range; 
 (ii) disable the electric compressor when the temperature of the second section of the cabin is less than the minimum temperature; 
 (iii) maintain the electric compressor disabled until the temperature of the second section of the cabin is greater than a maximum temperature defining an upper limit of the predetermined temperature range; and 
 (iv) when the temperature of the second section of the cabin is greater than the maximum temperature, repeat (i)-(iii). 
 
     
     
       4. The air conditioning system of  claim 2  wherein the control module is configured to, when the current of the electric compressor is not greater than the predetermined value:
 determine a compressor speed command based on the speed of the second blower; and 
 operate the electric compressor based on the compressor speed command. 
 
     
     
       5. The air conditioning system of  claim 4  wherein the control module is configured to:
 increase the compressor speed command as the speed of the second blower increases; and 
 decrease the compressor speed command as the speed of the second blower decreases. 
 
     
     
       6. The air conditioning system of  claim 4  wherein the control module is configured to:
 determine the compressor speed command based on the speed of the second blower until a voltage of the battery pack is less than a predetermined voltage; and 
 when the voltage of the battery pack is less than the predetermined voltage:
 (i) operate the electric compressor at a predetermined speed until the temperature of the second section of the cabin is less than a minimum temperature defining a lower limit of a predetermined temperature range; 
 (ii) disable the electric compressor when the temperature of the second section of the cabin is less than the minimum temperature; 
 (iii) maintain the electric compressor disabled until the temperature of the second section of the cabin is greater than a maximum temperature defining an upper limit of the predetermined temperature range; and 
 (iv) when the temperature of the second section of the cabin is greater than the maximum temperature, repeat (i)-(iii). 
 
 
     
     
       7. The air conditioning system of  claim 1  wherein the control module is configured to:
 operate the electric compressor at a predetermined speed for a predetermined period; 
 determine a current flow to the electric compressor when the predetermined period has passed; and 
 based on the current flow to the electric compressor, determine whether to control the speed of the electric compressor based on the temperature of the second section of the cabin of the vehicle or based on the speed of the second blower. 
 
     
     
       8. An air conditioning system of a vehicle having an internal combustion engine, comprising:
 an electric compressor; 
 a condenser that is configured to receive refrigerant output by the electric compressor and that transfers heat from the refrigerant within the condenser to air passing the condenser; 
 a fan that is configured to blow air across the condenser; 
 a first control valve; 
 a first evaporator that is configured to receive refrigerant from the condenser when the first control valve is open and that transfers heat from air passing the first evaporator to the refrigerant within the first evaporator; 
 a first blower that is configured to blow air across the first evaporator to a first section of a cabin of the vehicle; 
 a second control valve; 
 a second evaporator that is configured to receive refrigerant from the condenser when the second control valve is open and that transfers heat from air passing the second evaporator to the refrigerant within the second evaporator; 
 a second blower that is configured to blow air across the second evaporator to a second section of the cabin of the vehicle; 
 a control module that is configured to, when the internal combustion engine of the vehicle is off, the electric compressor is on, and the second blower is on and blowing air across the second evaporator:
 determine a compressor speed command; and 
 control a speed of the fan based on at least one of:
 a power consumption of an inverter drive; 
 a compressor discharge pressure; and 
 a speed of the electric compressor; and 
 
 
 wherein the inverter drive is configured to apply power to the electric compressor based on the compressor speed command. 
 
     
     
       9. The air conditioning system of  claim 8  wherein the control module is configured to control the speed of the fan based on the power consumption of the inverter drive including:
 decreasing the speed of the fan as the power consumption decreases; and 
 increasing the speed of the fan as the power consumption increases. 
 
     
     
       10. The air conditioning system of  claim 8  wherein the control module is configured to control the speed of the fan based on the compressor discharge pressure including:
 decreasing the speed of the fan as the compressor discharge pressure decreases; and 
 increasing the speed of the fan as the compressor discharge pressure increases. 
 
     
     
       11. The air conditioning system of  claim 8  wherein the control module is configured to control the speed of the fan based on the speed of the electric compressor including:
 decreasing the speed of the fan as the speed of the electric compressor decreases; and 
 increasing the speed of the fan as the speed of the electric compressor increases. 
 
     
     
       12. An air conditioning control method for a vehicle having an internal combustion engine, comprising:
 determining whether the internal combustion engine of the vehicle is off, 
 wherein a first evaporator is configured to receive refrigerant from a condenser when a first control valve is open and to transfer heat from air passing the first evaporator to the refrigerant within the first evaporator, 
 wherein a first blower is configured to blow air across the first evaporator to a first section of a cabin of the vehicle, and 
 wherein the condenser is configured to receive refrigerant output by an electric compressor that draws power from a battery pack and to transfer heat from the refrigerant within the condenser to air passing the condenser; 
 determining whether the electric compressor is on; 
 determining whether a second blower is on and blowing air across a second evaporator, 
 wherein the second evaporator is configured to receive refrigerant from the condenser when a second control valve is open and to transfer heat from air passing the second evaporator to the refrigerant within the second evaporator, and 
 wherein the second blower is configured to blow air across the second evaporator to a second section of the cabin of the vehicle; 
 when the internal combustion engine of the vehicle is off, the electric compressor is on, and the second blower is on and blowing air across the second evaporator, controlling a speed of the electric compressor based on at least one of:
 a temperature of the second section of the cabin of the vehicle; and 
 a speed of the second blower; and 
 
 based on a current of the electric compressor, determining whether to control the speed of the electric compressor:
 based on the temperature of the second section of the cabin of the vehicle; or 
 based on the speed of the second blower. 
 
 
     
     
       13. The air conditioning control method of  claim 12  further comprising:
 when the current of the electric compressor is greater than a predetermined value, controlling the speed of the electric compressor based on the temperature of the second section of the cabin of the vehicle; and 
 when the current of the electric compressor is not greater than the predetermined value, controlling the speed of the electric compressor based on the speed of the second blower. 
 
     
     
       14. The air conditioning control method of  claim 13  further comprising:
 (i) operating the electric compressor at a predetermined speed until the temperature of the second section of the cabin is less than a minimum temperature defining a lower limit of a predetermined temperature range; 
 (ii) disabling the electric compressor when the temperature of the second section of the cabin is less than the minimum temperature; 
 (iii) maintaining the electric compressor disabled until the temperature of the second section of the cabin is greater than a maximum temperature defining an upper limit of the predetermined temperature range; and 
 (iv) when the temperature of the second section of the cabin is greater than the maximum temperature, repeating (i)-(iii). 
 
     
     
       15. The air conditioning control method of  claim 13  wherein controlling the speed of the electric compressor based on the speed of the second blower when the current of the electric compressor is not greater than the predetermined value includes:
 determining a compressor speed command based on the speed of the second blower; and 
 operating the electric compressor based on the compressor speed command. 
 
     
     
       16. The air conditioning control method of  claim 15  further comprising:
 increasing the compressor speed command as the speed of the second blower increases; and 
 decreasing the compressor speed command as the speed of the second blower decreases. 
 
     
     
       17. The air conditioning control method of  claim 15  further comprising:
 determining the compressor speed command based on the speed of the second blower until a voltage of the battery pack is less than a predetermined voltage; and 
 when the voltage of the battery pack is less than the predetermined voltage:
 (i) operating the electric compressor at a predetermined speed until the temperature of the second section of the cabin is less than a minimum temperature defining a lower limit of a predetermined temperature range; 
 (ii) disabling the electric compressor when the temperature of the second section of the cabin is less than the minimum temperature; 
 (iii) maintaining the electric compressor disabled until the temperature of the second section of the cabin is greater than a maximum temperature defining an upper limit of the predetermined temperature range; and 
 (iv) when the temperature of the second section of the cabin is greater than the maximum temperature, repeating (i)-(iii). 
 
 
     
     
       18. The air conditioning control method of  claim 12  further comprising:
 operating the electric compressor at a predetermined speed for a predetermined period; 
 determining a current flow to the electric compressor when the predetermined period has passed; and 
 based on the current of the electric compressor, determining whether to control the speed of the electric compressor:
 based on the temperature of the second section of the cabin of the vehicle; or 
 based on the speed of the second blower. 
 
 
     
     
       19. An air conditioning control method for a vehicle having an internal combustion engine, comprising:
 determining whether the internal combustion engine of the vehicle is off, 
 wherein a first evaporator is configured to receive refrigerant from a condenser when a first control valve is open and to transfer heat from air passing the first evaporator to the refrigerant within the first evaporator, 
 wherein a first blower is configured to blow air across the first evaporator to a first section of a cabin of the vehicle, 
 wherein the condenser is configured to receive refrigerant output by an electric compressor and to transfer heat from the refrigerant within the condenser to air passing the condenser, and 
 wherein a fan is configured to blow air across the condenser; 
 determining whether the electric compressor is on; 
 determining whether a second blower is on and blowing air across a second evaporator, 
 wherein the second evaporator is configured to receive refrigerant from the condenser when a second control valve is open and to transfer heat from air passing the second evaporator to the refrigerant within the second evaporator, and 
 wherein the second blower is configured to blow air across the second evaporator to a second section of the cabin of the vehicle; and 
 when the internal combustion engine of the vehicle is off, the electric compressor is on, and the second blower is on and blowing air across the second evaporator:
 determining a compressor speed command; and 
 controlling a speed of the fan based on at least one of:
 a power consumption of an inverter drive; 
 a compressor discharge pressure; and 
 a speed of the electric compressor; and 
 
 wherein the inverter drive is configured to apply power to the electric compressor based on the compressor speed command. 
 
 
     
     
       20. The air conditioning control method of  claim 19  wherein controlling the speed of the fan based on at least one of the power consumption of the inverter drive, the compressor discharge pressure, and the speed of the electric compressor includes controlling the speed of the fan based on the power consumption of the inverter drive including:
 decreasing the speed of the fan as the power consumption decreases; and 
 increasing the speed of the fan as the power consumption increases. 
 
     
     
       21. The air conditioning control method of  claim 19  wherein controlling the speed of the fan based on at least one of the power consumption of the inverter drive, the compressor discharge pressure, and the speed of the electric compressor includes controlling the speed of the fan based on the compressor discharge pressure including:
 decreasing the speed of the fan as the compressor discharge pressure decreases; and 
 increasing the speed of the fan as the compressor discharge pressure increases. 
 
     
     
       22. The air conditioning control method of  claim 19  wherein controlling the speed of the fan based on at least one of the power consumption of the inverter drive, the compressor discharge pressure, and the speed of the electric compressor includes controlling the speed of the fan based on the speed of the electric compressor including:
 decreasing the speed of the fan as the speed of the electric compressor decreases; and 
 increasing the speed of the fan as the speed of the electric compressor increases.